--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/html/story-writer.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,273 @@
+// Copyright (C) 2022 Artifex Software, Inc.
+//
+// This file is part of MuPDF.
+//
+// MuPDF is free software: you can redistribute it and/or modify it under the
+// terms of the GNU Affero General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+//
+// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+// details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
+//
+// Alternative licensing terms are available from the licensor.
+// For commercial licensing, see <https://www.artifex.com/> or contact
+// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
+// CA 94129, USA, for further information.
+
+
+#include "mupdf/fitz/story-writer.h"
+
+#include <string.h>
+
+/*
+ * Internal state for fz_write_story() to allow passing of page_num to
+ * positionfn.
+ */
+typedef struct
+{
+	fz_write_story_positionfn *positionfn;
+	void *positionfn_ref;
+	int page_num;
+} positionfn_state;
+
+/*
+ * Intermediate callback for fz_write_story() which calls the user-supplied
+ * callback.
+ */
+static void positionfn_state_fn(fz_context *ctx, void *arg, const fz_story_element_position *position)
+{
+	positionfn_state *state = arg;
+	fz_write_story_position do_position;
+	do_position.element = *position;
+	do_position.page_num = state->page_num;
+	state->positionfn(ctx, state->positionfn_ref, &do_position);
+}
+
+void fz_write_story(
+		fz_context *ctx,
+		fz_document_writer *writer,
+		fz_story *story,
+		fz_write_story_rectfn rectfn,
+		void *rectfn_ref,
+		fz_write_story_positionfn positionfn,
+		void *positionfn_ref,
+		fz_write_story_pagefn pagefn,
+		void *pagefn_ref
+		)
+{
+	fz_rect filled = {0};
+	int rect_num = 0;
+	positionfn_state positionfn_state;
+
+	positionfn_state.positionfn = positionfn;
+	positionfn_state.positionfn_ref = positionfn_ref;
+	positionfn_state.page_num = 0;
+
+	fz_var(positionfn_state);
+
+	fz_try(ctx)
+	{
+		fz_device *dev = NULL;
+		for(;;)
+		{
+			fz_matrix ctm = fz_identity;
+			fz_rect rect;
+			fz_rect mediabox;
+			int newpage;
+			int more;
+
+			newpage = rectfn(ctx, rectfn_ref, rect_num, filled, &rect, &ctm, &mediabox);
+			rect_num += 1;
+			if (newpage)
+				positionfn_state.page_num += 1;
+
+			more = fz_place_story(ctx, story, rect, &filled);
+
+			if (positionfn)
+			{
+				fz_story_positions(ctx, story, positionfn_state_fn, &positionfn_state /*ref*/);
+			}
+
+			if (writer)
+			{
+				if (newpage)
+				{
+					if (dev)
+					{
+						if (pagefn)
+							pagefn(ctx, pagefn_ref, positionfn_state.page_num, mediabox, dev, 1 /*after*/);
+						fz_end_page(ctx, writer);
+					}
+					dev = fz_begin_page(ctx, writer, mediabox);
+					if (pagefn)
+						pagefn(ctx, pagefn_ref, positionfn_state.page_num, mediabox, dev, 0 /*after*/);
+				}
+				assert(dev);
+				fz_draw_story(ctx, story, dev, ctm);
+				if (!more)
+				{
+					if (pagefn)
+						pagefn(ctx, pagefn_ref, positionfn_state.page_num, mediabox, dev, 1 /*after*/);
+					fz_end_page(ctx, writer);
+				}
+			}
+			else
+			{
+				fz_draw_story(ctx, story, NULL /*dev*/, ctm);
+			}
+			if (!more)
+				break;
+		}
+	}
+	fz_always(ctx)
+	{
+	}
+	fz_catch(ctx)
+	{
+		fz_rethrow(ctx);
+	}
+}
+
+/*
+ * Copies a fz_write_story_position, taking care to use fz_strdup() for
+ * strings.
+ */
+static void do_position_copy(fz_context *ctx, fz_write_story_position *to, const fz_write_story_position *from)
+{
+	*to = *from;
+	to->element.id = NULL;
+	to->element.text = NULL;
+	if (from->element.id) to->element.id = fz_strdup(ctx, from->element.id);
+	if (from->element.text) to->element.text = fz_strdup(ctx, from->element.text);
+}
+
+static void positions_clear(fz_context *ctx, fz_write_story_positions *positions)
+{
+	int i;
+	/* positions_clear() will have used fz_strdup() for strings, so free
+	them first: */
+	for (i=0; i<positions->num; ++i)
+	{
+		fz_free(ctx, (void*) positions->positions[i].element.id);
+		fz_free(ctx, (void*) positions->positions[i].element.text);
+	}
+	fz_free(ctx, positions->positions);
+	positions->positions = NULL;
+	positions->num = 0;
+}
+
+static int buffers_identical(fz_context *ctx, fz_buffer *a, fz_buffer *b)
+{
+	size_t a_len;
+	size_t b_len;
+	unsigned char *a_data;
+	unsigned char *b_data;
+	a_len = fz_buffer_storage(ctx, a, &a_data);
+	b_len = fz_buffer_storage(ctx, b, &b_data);
+	return a_len == b_len && !memcmp(a_data, b_data, a_len);
+}
+
+
+static void stabilize_positionfn(fz_context *ctx, void *ref, const fz_write_story_position *position)
+{
+	fz_write_story_positions *positions = ref;
+	/* Append <element> plus page_num to items->items[]. */
+	positions->positions = fz_realloc(ctx, positions->positions, sizeof(*positions->positions) * (positions->num + 1));
+	do_position_copy(ctx, &positions->positions[positions->num], position);
+	positions->num += 1;
+}
+
+
+void fz_write_stabilized_story(
+		fz_context *ctx,
+		fz_document_writer *writer,
+		const char *user_css,
+		float em,
+		fz_write_story_contentfn contentfn,
+		void *contentfn_ref,
+		fz_write_story_rectfn rectfn,
+		void *rectfn_ref,
+		fz_write_story_pagefn pagefn,
+		void *pagefn_ref,
+		fz_archive *zip
+		)
+{
+	fz_write_story_positions positions = {0};
+	fz_story *story = NULL;
+	fz_buffer *content = NULL;
+	fz_buffer *content_prev = NULL;
+	int stable = 0;
+
+	positions.positions = NULL;
+	positions.num = 0;
+
+	fz_var(positions);
+	fz_var(story);
+	fz_var(content);
+
+	fz_try(ctx)
+	{
+		content = fz_new_buffer(ctx, 0 /*capacity*/);
+		content_prev = fz_new_buffer(ctx, 0 /*capacity*/);
+
+		/* Iterate until stable. */
+		for(;;)
+		{
+			/* Move <content> to <content_prev> and make <content>
+			contain new html from contentfn(). */
+			{
+				fz_buffer *content_tmp = content;
+				content = content_prev;
+				content_prev = content_tmp;
+			}
+			fz_clear_buffer(ctx, content);
+			contentfn(ctx, contentfn_ref, &positions, content);
+
+			if (buffers_identical(ctx, content, content_prev))
+			{
+				/* Content is unchanged, so this is the last iteration and we
+				will use <writer> not NULL. */
+				stable = 1;
+			}
+
+			/* Create story from new content. */
+			fz_drop_story(ctx, story);
+			story = NULL;
+			story = fz_new_story(ctx, content, user_css, em, zip);
+
+			/* Layout the story, gathering toc information as we go. */
+			positions_clear(ctx, &positions);
+			fz_write_story(
+					ctx,
+					(stable) ? writer : NULL,
+					story,
+					rectfn,
+					rectfn_ref,
+					stabilize_positionfn,
+					&positions /*positionfn_ref*/,
+					pagefn,
+					pagefn_ref
+					);
+
+			if (stable)
+				break;
+		}
+	}
+	fz_always(ctx)
+	{
+		fz_drop_story(ctx, story);
+		fz_drop_buffer(ctx, content);
+		fz_drop_buffer(ctx, content_prev);
+		positions_clear(ctx, &positions);
+	}
+	fz_catch(ctx)
+	{
+		fz_rethrow(ctx);
+	}
+}